1. Technical Field
The present invention relates to a signal measurement apparatus, a signal measurement method, a recording medium, and a test apparatus. In particular, the present invention relates to a signal measurement apparatus, a signal measurement method, a recording medium, and a test apparatus for measuring a plurality of signals under measurement using a digital comparator such as a voltage comparator.
2. Related Art
A conventional method for measuring the rise time or the fall time of a signal under measurement (sometimes referred to hereinafter as “the rise/fall time”) involves observing the transition edges of the signal under measurement using a sampling oscilloscope. Japanese Patent Application Publication No. 2002-228687 discloses a technique for calculating the rise/fall time by obtaining the timing difference between 10% level cross-point of the signal amplitude and the 90% level cross-point of the signal amplitude.
When measuring with the sampling oscilloscope, however, it is difficult to achieve sufficient measurement accuracy because the sampling frequency is low. Since waveform data of the level cross timing outside of the measurement target range is also sampled, a long sampling time is required to achieve the desired measurement accuracy. Since waveform measurement accuracy of approximately 8 bits is required for sufficient measurement accuracy, this technique cannot be applied to a semiconductor test apparatus that samples a waveform with a 1-bit comparator.